<html>  
  <head>  
        <meta charset="utf-8">  
        <title>3.4 绘制矢量图</title>  
  </head> 
<body>

<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script> 
<script>  
var width  = 400;	//SVG绘制区域的宽度
var height = 400;	//SVG绘制区域的高度
	
var svg = d3.select("body")			//选择<body>
			.append("svg")			//在<body>中添加<svg>
			.attr("width", width)	//设定<svg>的宽度属性
			.attr("height", height);//设定<svg>的高度属性
			
svg.append("circle")
	.attr("cx","50px")
	.attr("cy","50px")
	.attr("r","50px")
	.attr("fill","blue");
	
</script> 

</body>

</html>